It is Time to Act: 2 Degrees is the Limit

We are calling on world leaders to take urgent action on climate change to limit global warming to less than 2 degrees centigrade. Some of the world’s leading thinkers and practitioners have signed this statement. Please join them, add your voice to theirs to call for decisive action on climate change. The message will be presented to world leaders on the occasion of the Climate Leaders’ Summit, convened by UN Secretary-General Ban Ki-moon at the United Nations, New York City, on September 23, 2014.

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Message on Climate Change to World Leaders

Human-induced climate change is an issue beyond politics. It transcends parties, nations, and even generations. For the first time in human history, the very health of the planet, and therefore the bases for future economic development, the end of poverty, and human wellbeing, are in the balance. If we were facing an imminent threat from beyond Earth, there is no doubt that humanity would immediately unite in common cause. The fact that the threat comes from within – indeed from ourselves – and that it develops over an extended period of time does not alter the urgency of cooperation and decisive action.

The world has agreed to limit the mean temperature increase to less than 2-degrees Centigrade (2°C). Even a 2°C increase will carry us to dangerous and unprecedented conditions not seen on Earth during the entire period of human civilization. Various physical feedbacks – in the Arctic, the oceans, the rainforests, and the tundra – could multiply a 2°C temperature increase into vastly higher temperatures and climate disruption. For this reason many scientists and some countries advocate for 1.5°C or even stricter targets.

To give up on the 2°C limit, on the other hand, would be reckless and foolish. We would abandon our remaining chance to stay within a safe operating space for humanity and that of millions of other species. By holding the 2°C limit, we would retain the global option to adopt an even more stringent emission reduction limit in line with evolving scientific knowledge and technological capacities.

The 2°C limit, or an even stronger target, can be met through long-term national strategies and concerted global cooperation. All countries must commit to a deep decarbonization of their energy systems, shifting from high-carbon energy (coal, oil, and natural gas) to low-carbon energy of various kinds (e.g. wind, solar, nuclear, carbon capture and sequestration, known as CCS). Low-carbon electricity plus massive gains in energy efficiency and the electrification of vehicles, heating and cooling systems of commercial as well as residential buildings can lead to a dramatic reduction of carbon-dioxide emissions alongside a growing economy. Changes in lifestyle patterns and urban planning can make another important contribution. The many co-benefits of decarbonization with the deployment of sustainable energy, information and communication technologies will include cleaner air and water, enhanced biodiversity, and security of domestic renewable energy resources. Targeted efforts are also required to decarbonize key industries. Finally, countries need to curb greenhouse gas emissions resulting from agriculture, livestock, and land-use change, such as deforestation. They must also manage and restore ecosystems to ensure they can serve as a significant net sink for greenhouse gas emissions.

The technological transition during the first half of the 21st century is within reach, especially in light of massive advances in knowhow in recent years. In many parts of the world and in some contexts, solar and wind power are already at “grid parity.” Large-scale deployment of electric vehicles, carbon-capture and sequestration, next-generation nuclear power plants for those countries deploying nuclear power, and other low-carbon energy technologies are all within reach. They can be pushed to commercial readiness and large-scale deployment through concerted public and private programs of research, development, demonstration, and diffusion (RDD&D) on a global scale.

We have nearly exhausted the Earth’s carbon budget, which measures the cumulative emissions of CO2 that will likely keep the planet within the 2°C limit. Only through a drastic reduction of carbon emissions between now and 2050, en route to a zero-net emission economy in the second half of the century, can we meet the challenge of remaining below 2°C. Yet, deep decarbonization can be accomplished. As President John F. Kennedy said a half-century ago, “We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills…”

In our time, humanity again must choose, this time to save our planet from shortsightedness, greed, and apathy to avoid catastrophic climate change. This time too, we must organize and measure the best of our energies and skills to stay within 2°C. We call upon you, world leaders, to recognize the gravity of the situation, and to call upon all of us to rise to the occasion. We owe nothing less to ourselves, to future generations, and to Earth itself.